Complex Permittivity Extraction of Dielectric Samples in Waveguide

Document Type

Conference Proceeding

Publication Date



This paper describes a method to determine the relative permittivity of a dielectric material in printed circuit board. The dielectric sample in a PCB is placed to form a finline discontinuity of finite length in a waveguide. S-parameter of a discontinuity from an empty waveguide to finline and back to empty waveguide is measured. An error function that compares the measured and calculated S-parameters of the discontinuity is minimized to extract the permittivity of the sample. The optimization is based on a practical quasi-Newton algorithm. The calculated value of the S-parameter used in the error function is obtained from the modal expansion of the fields in the empty waveguide and the finline structure. Field matching is done at the discontinuity to yield the theoretically calculated S-paramters.


Copyright 2008 IEEE

A link to content has been provided for authorized users.

Publication Title

2008 International Conference on Microwave and Millimeter Wave Technology

Published Citation

Balaji, U. (2008, April). Complex permittivity extraction of dielectric samples in waveguide. In 2008 International Conference on Microwave and Millimeter Wave Technology (Vol. 3, pp. 1294-1297). IEEE. https://doi.org/ 10.1109/ICMMT.2008.4540673